Exhaust gas cooling adapter

ABSTRACT

An exhaust gas cooling adapter arranged between an exhaust port opening to a cylinder head of an engine and an exhaust manifold is equipped with an exhaust gas flow channel which is provided inside the exhaust gas cooling adapter and through which an exhaust gas from the exhaust port flows to the exhaust manifold, and a cooling liquid flow channel which is formed in a wall portion of the exhaust gas cooling adapter that surrounds the exhaust gas flow channel to cool the exhaust gas flowing through the exhaust gas flow channel. The wall portion has a blockage portion formed by blocking a through-hole provided between an outside and the cooling liquid flow channel. This blockage portion has a region located in the cooling liquid flow channel and arranged at a position other than a collision position of a cooling liquid flowing through the cooling liquid flow channel.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2010-137215 filed on Jun. 16, 2010 including the specification, drawings and abstract is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an exhaust gas cooling adapter that is arranged between an exhaust port opening to a cylinder head of an internal combustion engine and an exhaust manifold, and has an exhaust gas flow channel, through which an exhaust gas from the exhaust port flows to the exhaust manifold, formed therein and a cooling liquid flow channel, by which the exhaust gas flowing though the exhaust gas flow channel is cooled, formed in a wall portion of the exhaust gas cooling fan that surrounds this exhaust flow channel.

2. Description of Related Art

There is known an art for cooling exhaust gas to prevent a thermal damage to an exhaust system of an internal combustion engine, such as an exhaust gas purification catalyst or the like. For example, in Japanese Patent Application Publication No. 11-49096 (JP-A-11-49096), there is disclosed an art in which a coupling member is provided between a cylinder head and an exhaust manifold and is provided with a coolant flow channel. This coolant flow channel is formed as an open recess portion, and a coolant introduced from both lower ends of the coolant flow channel immediately flows into a coolant flow channel on the exhaust manifold side.

In some cases, the coolant flow channel is not designed as an open recess portion as described in Japanese Patent Application Publication No. 11-49096 (JP-A-11-49096) but is formed inside a coupling member, and an exhaust gas cooling adapter that introduces a coolant into this coolant flow channel via an inflow port and discharges the coolant from an outflow port is formed. With this shape, when air flows inside and then remains as bubbles, a decrease in cooling efficiency may result from a decrease in the area of contact between a wall surface of the coolant flow channel and the coolant. Further, when the coolant is heated by the exhaust gas, a decrease in cooling efficiency or boiling may be caused. Alternatively, a decrease in cooling efficiency or boiling may result from the creation of an internal region where the coolant dwells.

Especially in the case where the exhaust gas cooling adapter is molded through casting, the coolant flow channel located inside is formed by a core, and the core must be crushed and discharged after casting. Thus, a sand removal hole for discharging cast sand constituting the core is formed through the exhaust gas cooling adapter that has just been cast. This sand removal hole is blocked with a plug body or the like, but a dent is formed on the coolant flow channel side through a blockage portion thus constructed. The dent in this cooling flow channel is filled with the coolant during use, and the air mixed in the flow of the coolant may flow into the dent in some cases.

Normally, even when the coolant or the air mixed in the flow of the coolant temporarily enters the dent as described above, it is discharged to the outside of the dent due to the flow of the coolant. However, when the coolant flow channel adopts a certain construction, the coolant does not flow such that the, coolant or bubbles are discharged from the dent. In some cases, the coolant may dwell in the dent, or the air that has flowed into the coolant flow channel may remain as bubbles.

SUMMARY OF THE INVENTION

The invention provides an exhaust gas cooling adapter capable of preventing a cooling liquid from dwelling in a cooling liquid flow channel of an exhaust gas cooling adapter or preventing bubblers from remaining therein.

An aspect of the invention relates to an exhaust gas cooling adapter. This exhaust gas cooling adapter is arranged between an exhaust port opening to a cylinder head of an internal combustion engine and an exhaust manifold, and has an exhaust gas flow channel, through which an exhaust gas from the exhaust port flows to the exhaust manifold, formed therein and a cooling liquid flow channel, by which the exhaust gas flowing through the exhaust gas flow channel is cooled, formed in a wall portion of the exhaust gas cooling adapter that surrounds this exhaust gas flow channel. The wall portion of the exhaust gas cooling adapter has a blockage portion formed by blocking a through-hole provided between an outside and the cooling liquid flow channel. This blockage portion has a region located in the cooling liquid flow channel and arranged at a position other than a collision position of a cooling liquid flowing through the cooling liquid flow channel.

A dent is likely to be produced in a wall surface of that region of the blockage portion which is located in the cooling liquid flow channel. When this region is a collision position of the cooling liquid flowing through the cooling liquid flow channel, air flows into a dent region and is likely to produce bubbles. Furthermore, since the cooling liquid collides with the cooling liquid and bubbles that have entered this dent region, the cooling liquid and bubbles are unlikely to be discharged in either direction. It is therefore difficult to discharge the cooling liquid and bubbles from the dent region.

However, according to the exhaust gas cooling adapter according to the aspect of the invention, the region of the blockage portion located in the cooling liquid flow channel is arranged at the position other than the collision position of the cooling liquid flowing through the cooling liquid flow channel. Thus, even when a dent is produced in the region, air is unlikely to enter the dent.

Furthermore, even when air enters the dent to temporarily produce bubbles, a pressure applied to these bubbles by the flow of the cooling liquid does not serve to confine the bubbles, and the pressure resulting from the flow of the cooling liquid generates a pressure applied in such a direction as to discharge the bubbles from the dent, so that the bubbles are likely to move. Thus, the bubbles are easily discharged from the dent.

This also holds true for the cooling liquid in the dent. The pressure applied to the cooling liquid by the flow of the cooling liquid does not serve to confine the cooling liquid within the dent to make the cooling liquid dwell therein, and the pressure resulting from the flow of the cooling liquid generates a pressure applied in such a direction as to discharge the cooling liquid from the dent, so that the cooling liquid inside the dent is likely to move. Thus, the cooling liquid can be easily discharged from the dent, and hence can be replaced.

Accordingly, the cooling liquid can be prevented from dwelling in the cooling liquid flow channel of the exhaust gas cooling adapter, and bubbles can be prevented from remaining therein.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

FIGS. 1A to 1C are illustrative views of the construction of an exhaust gas cooling adapter according to the first embodiment of the invention;

FIGS. 2A to 2D are illustrative views of the construction of the exhaust gas cooling adapter according to the first embodiment of the invention;

FIGS. 3A and 3B are cutaway illustrative views of the exhaust gas cooling adapter according to the first embodiment of the invention;

FIGS. 4A and 4B are cutaway illustrative views of the exhaust gas cooling adapter according to the first embodiment of the invention;

FIG. 5 is a cross-sectional view of the exhaust gas cooling adapter according to the first embodiment of the invention;

FIGS. 6A to 6C are illustrative views of the construction of an exhaust gas cooling adapter according to the second embodiment of the invention;

FIGS. 7A to 7D are illustrative views of the construction of the exhaust gas cooling adapter according to the second embodiment of the invention;

FIGS. 8A and 8B are cutaway illustrative views of the exhaust gas cooling adapter according to the second embodiment of the invention;

FIGS. 9A and 9B are cutaway illustrative views of the exhaust gas cooling adapter according to the second embodiment of the invention; and

FIGS. 10A and 10B are illustrative views of the construction of an exhaust gas cooling adapter according to another embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS First Embodiment

FIGS. 1 and 2 show the construction of an exhaust gas cooling adapter 2 to which the aforementioned invention is applied. FIG. 1A is a plan view, FIG. 1B is a front view, FIG. 1C is a bottom view, FIG. 2A is a back view, FIG. 2B is a left lateral view, FIG. 2C is a right lateral view, and FIG. 2D is a perspective view.

As indicated by broken lines in FIG. 2B, this exhaust gas cooling adapter 2 is arranged between an exhaust port 4 a opening to a cylinder head 4 of an internal combustion engine and an exhaust manifold 6 to cool an exhaust gas discharged from the exhaust port 4 a and discharge the exhaust gas to the exhaust manifold 6, thereby preventing a thermal damage to an exhaust system of the internal combustion engine. It should be noted that although the internal combustion engine is a four-cylinder engine in this embodiment of the invention, an inline four-cylinder engine or a V-type eight-cylinder engine may be employed as the internal combustion engine. Alternatively, the invention is made applicable to other types of internal combustion engines such as a V-type six-cylinder engine and the like by changing the internal construction of the exhaust gas cooling adapter 2, especially the number of exhaust gas flow channels.

This exhaust gas cooling adapter 2 is cast from a metallic material, for example, an aluminum alloy, an iron alloy or the like, and forms a cylinder head-side connection face 10 to which each exhaust gas introduction port 8 opens on an exhaust gas upstream side. In accordance with the positions and numbers of exhaust ports 4 a in the cylinder head 4, four exhaust gas introduction ports 8 are provided in linear arrangement in this case. It should be noted that when the invention is applied to a V-type six-cylinder engine, three exhaust gas introduction ports 8 are provided in linear arrangement in accordance with exhaust ports for three cylinders at each bank.

An exhaust manifold-side connection face 14 to which each exhaust gas discharge port 12 opens is formed on an exhaust gas downstream side. In accordance with the exhaust gas introduction ports 8, four exhaust gas discharge ports 12 are provided in linear arrangement.

These exhaust gas introduction ports 8 are connected to these exhaust gas discharge ports 12 by four exhaust gas flow channels 16 formed in the exhaust gas cooling adapter 2 respectively. Bolt fastening portions 10 a for fastening the exhaust gas cooling adapter 2 itself to an adapter connection face 4 b on the cylinder head 4 side by bolts are formed at peripheral portions of the cylinder head-side connection face 10 in the exhaust gas cooling adapter 2. The bolts are inserted through bolt insertion holes 10 b formed through these bolt fastening portions 10 a and screwed into screw holes opening to the adapter connection face 4 b on the cylinder head 4 side respectively, so that the exhaust gas cooling adapter 2 can be fixed to the cylinder head 4 through the fastening of the bolts. Thus, the exhaust ports 4 a on the cylinder head 4 side can be connected to the exhaust gas flow channels 16 on the exhaust gas cooling adapter 2 respectively.

Furthermore, bolt fastening portions 14 a for fastening the exhaust manifold 6 by bolts are formed at peripheral portions of the exhaust manifold-side connection face 14 in the exhaust gas cooling adapter 2. Screw holes 14 b are formed through the bolt fastening portions 14 a respectively. The bolts are screwed via insertion holes formed through a flange 6 a of the exhaust manifold 6 respectively, so that the exhaust manifold 6 is fastened by the bolts and connected. Thus, the exhaust gas flow channels 16 of the exhaust gas cooling adapter 2 can be connected to exhaust gas flow channels 6 b of the exhaust manifold 6 respectively.

It should be noted that since the interval among the exhaust ports 4 a of the cylinder head 4 is set larger than the interval among opening portions of the exhaust manifold 6, the interval among the exhaust gas introduction ports 8 of the cylinder head-side connection face 10 is larger than the interval among the exhaust gas discharge ports 12 of the exhaust manifold-side connection face 14.

As shown in FIGS. 3 and 4, a water jacket 18 as a cooling liquid flow channel is formed around the exhaust gas flow channels 16 in a wall portion of the exhaust gas cooling adapter 2. It should be noted herein that FIG. 3A is a perspective view of a state cut away along a line in FIG. 2C viewed in a worm's eye manner. FIG. 3B is a cross-sectional view taken also along the line FIG. 4A is a perspective view of a state cut away along a line IV-IV in FIG. 1B. FIG. 4B is a cross-sectional view taken also along the line IV-IV. It should be noted that the flow of the cooling liquid through the water jacket 18 is indicated by arrows of alternate long and short dash lines, and that the flow of exhaust gas flow through the exhaust gas flow channels 16 is indicated by arrows of broken lines.

As shown in the drawings, the water jacket 18 is composed of cooling liquid flow channels 18 a, 18 b, 18 c, and 18 d formed around the arrangement of the exhaust gas flow channels 16, and cooling liquid flow channels 18 e, 18 f, and 18 g formed among the exhaust gas flow channels 16. The cooling liquid in this water jacket 18 is introduced from a cooling liquid introduction portion 20 located below, and is discharged from a cooling liquid discharge portion 22 located above. It should be noted that regional coupling portions 19 a, 19 b, and 19 c protrude among the exhaust gas flow channels 16 from the cylinder head-side connection face 10 side, namely, from an upstream side of exhaust gas flow to reinforce the entire exhaust gas cooling adapter 2 at positions of the cooling liquid flow channels 18 e, 18 f, and 18 g among the exhaust gas flow channels 16 respectively. Thus, wall portions 16 a around the respective exhaust gas flow channels 16 are connected leaving the cooling liquid flow channels 18 e, 18 f, and 18 g, thereby enhancing the rigidity of the exhaust gas cooling adapter 2.

As described above, the exhaust gas cooling adapter 2 is a cast body made of a metal, and a core is used to form the water jacket 18 located inside at the time of casting. Accordingly, it is necessary to crush the core and take out cast sand therefrom after casting. Thus, through-holes 24 a, 26 a, and 28 a are formed as sand removal holes. The crushed cast sand is then taken out from these through-holes 24 a to 28 a, and then the through-holes 24 a to 28 a are blocked by fitting plus bodies 24 b, 26 b, and 28 b thereinto respectively, so that blockage portions 24, 26, and 28 are formed respectively. It should be noted that the cooling liquid introduction portion 20 and the cooling liquid discharge portion 22 as well as the through-holes 24 a to 28 a of the blockage portions 24 to 28 are utilized as sand removal holes.

The through-holes 24 a to 28 a are blocked with the plug bodies 24 b to 28 b respectively. Therefore, as shown in a cross-sectional view of FIG. 5, dents 24 c, 26 c, and 28 e are formed in an inner face of the water jacket 18. FIG. 5 is a cross-sectional view showing further a wall portion 2 a of an outer peripheral region of the exhaust gas cooling adapter 2 in a manner cut away at positions of central axes of the respective through-holes 24 a to 28 a in FIG. 3.

In the water jacket 18, the wall portion 2 a of the outer peripheral region of the cooling liquid flow channel 18 a, which is located below in the vertical direction when being arranged between the cylinder head 4 and the exhaust manifold 6, is provided with a single blockage portion 28. This blockage portion 28 is a region obtained by blocking the through-hole 28 a, which makes it possible to remove sand from and observe the interiors of the cooling liquid flow channels 18 g between the exhaust gas flow channels 16 shown on the right in FIG. 5 and the cooling liquid flow channels 18 a and 18 d located therearound, with the plug body 28 b.

This blockage portion 28 is provided at a position of a lower extension of the cooling liquid flow channel 18 g. Thus, the dent 28 c formed inside by blocking the through-hole 28 a with the plug body 28 b faces the cooling liquid flow channel 18 g from a lower end side. It should be noted that the flow of the cooling liquid through the cooling liquid flow channel 18 g is oriented reversely to the dent 28 c.

In the water jacket 18, the wall portion 2 a of the outer peripheral region of the cooling liquid flow channel 18 d, which is located above in the vertical direction when being arranged between the cylinder head 4 and the exhaust manifold 6, is provided with two blockage portions 24 and 26. Out of these blockage portions 24 and 26, the blockage portion 26 present at the left end exists at a connection position between the cooling liquid flow channel 18 b present at the end of the arrangement of the exhaust gas flow channels 16 and the cooling liquid flow channel 18 d located above.

This blockage portion 26 is a region obtained by blocking the through-hole 26 a, which makes it possible to remove sand from and observe the interiors of the cooling liquid flow channel 18 b located at the left end and the cooling liquid flow channels 18 a and 18 d located therearound, with the plug body 26 b. Accordingly, the dent 26 c formed by blocking the through-hole 26 a with the plug body 26 b exists in the flow of the cooling liquid flowing in one direction from the cooling liquid flow channel 18 b located at the left end to the cooling liquid flow channel 18 d located above.

The blockage portion 24 located at the center of the cooling liquid flow channel 18 d located above in the vertical direction is a region obtained by blocking the through-hole 24 a, which makes it possible to remove sand from and observe the interiors of the cooling liquid flow channel 18 f between the exhaust gas flow channels 16 shown at the center of FIG. 5 and the cooling liquid flow channels 18 a and 18 d located therearound, with the plug body 24 b.

In a head-on view as shown in FIG. 5, this blockage portion 24 is provided at a position of an upper end extension of the cooling liquid flow channel 18 f. However, as shown in FIG. 4, the regional coupling portion 19 b is actually located below the blockage portion 24, and the blockage portion 24 is formed at a position deviant from the position of the upper end extension of the cooling liquid flow channel 18 f. Accordingly, the dent 24 c as that region of the blockage portion 24 which is located in the water jacket 18 is arranged at a position other than a collision position of the cooling liquid flowing upward through the cooling liquid flow channel 18 f.

Accordingly, as shown in FIGS. 4 and 5, the dent 24 c faces only the flow of the cooling liquid flowing laterally from the left to the right with respect to the dent 24 c. It should be noted that the opening portion 20 a of the cooling liquid introduction portion 20 makes it possible to remove sand from and observe the cooling liquid flow channel 18 e between the exhaust gas flow channels 16 on the left in FIG. 5 and the cooling liquid flow channels 18 a and 18 d located therearound, and that the opening portion 22 a of the cooling liquid discharge portion 22 makes it possible to remove sand from and observe the cooling liquid flow channel 18 c located at the right end of the arrangement of the exhaust gas flow channels 16 and the cooling liquid flow channels 18 a and 18 d located therearound.

According to the first embodiment of the invention described above, the following effects are obtained. (1) In the blockage portions 24 to 28, the through-holes 24 a to 28 a are blocked with the plug bodies 24 b to 28 b respectively, so that the dents 24 c to 28 c are produced in the water jacket 18 respectively. Accordingly, when the cooling liquid flowing through the water jacket 18 collides with the positions of the blockage portions 24 to 28 in the case where air is mixed in the cooling liquid, the air may flow into the dents 24 c to 28 c and remain as bubbles without being discharged. Further, even when the air does not flow into the dents 24 c to 28 c, the cooling liquid itself may dwell therein.

However, as shown in FIG. 5, as for the blockage portion 28 located below, the cooling liquid does not flow in such a direction as to collide with the dent 28 c, and the dent 28 c opens upward. Thus, no air enters the dent 28 c. Even when air enters the dent 28 c, it is immediately discharged due to a buoyant force of bubbles and the flow of the cooling liquid flowing laterally. Even when only the cooling liquid enters the dent 28 c, it is immediately discharged and replaced due to a buoyant force resulting from a rise in temperature and the flow of the cooling liquid flowing laterally.

As for the blockage portion 26 located at the left end, the dent 26 c opens downward. However, the cooling liquid flows in one direction in a curved manner, namely, in a horizontal direction from diagonally below. Accordingly, the cooling liquid does not flow in such a direction as to collide with the dent 26 c. Thus, even when air enters the dent 26 c, the air in the dent 26 c is discharged instead of remaining as bubbles, due to the flow of the cooling liquid flowing away laterally at the end. Even when only the cooling liquid enters the dent 26 e, it is also immediately discharged and replaced without dwelling therein.

As for the blockage portion 24 located above, the dent 24 c opens downward. In the case where the cooling liquid flows through the cooling liquid flow channel 18 f formed between the exhaust gas flow channels 16 in such a manner as to collide with the dent 24 c, that is, in the case where the blockage portion 24 is located at the position of the upper end extension of the cooling liquid flow channel 18 f, when air is mixed into the flow of the cooling liquid through the cooling liquid flow channel 18 f, the air is introduced into the dent 24 c. Then, being pressed by the flow of the cooling liquid, the air cannot escape from the dent 24 c and may continue to remain as bubbles. Even when only the cooling liquid enters the dent 24 c, it may dwell in the dent 24 c by being pressed by the flow of the cooling liquid.

However, as shown in FIG. 4, this dent 24 c does not exist at the position of the upper end extension of the cooling liquid flow channel 18 f, but is deviated in a direction of exhaust gas flow through the exhaust gas flow channels 16 (a direction perpendicular to the direction of the arrangement of the exhaust gas flow channels 16) (actually deviated upstream with respect to exhaust gas flow) and arranged above the regional coupling portion 19 b. Thus, the cooling liquid flowing through the cooling liquid flow channel 18 f does not collide with the dent 24 c, and the cooling liquid only flows through the cooling liquid flow channel 18 d laterally (in the horizontal direction).

Accordingly, even when air enters the dent 24 c, the air in the dent 24 c is discharged instead of remaining as bubbles, due to the flow of the cooling liquid flowing away laterally. By the same token, even when only the cooling liquid enters the dent 24 c, it is discharged from the dent 24 c and replaced without dwelling therein, due to the flow of the cooling liquid flowing away laterally.

In this manner, bubbles can be prevented from remaining in the water jacket 18 of the exhaust gas cooling adapter 2, and the cooling liquid can be prevented from dwelling therein. Thus, even when the cooling liquid in the exhaust gas cooling adapter 2 is heated through the transmission of heat from the exhaust manifold 6 or the exhaust gas flowing through the exhaust gas flow channels 16, a decrease in cooling efficiency or boiling can be prevented from being caused.

(2) It should be noted in this embodiment of the invention that the aforementioned dent 24 c is located, namely, the through-hole 24 a is located such that the interior of the cooling liquid flow channel 18 f is visible via this through-hole 24 a, before the through-hole 24 a is blocked with the plug body 24 b.

Thus, in addition to the aforementioned effect (1), there is no hindrance to the removal of sand from the interior of the cooling liquid flow channel 18 or the observation thereof.

Second Embodiment

FIGS. 6, 7, 8 and 9 show the construction of an exhaust gas cooling adapter 102 according to the second embodiment of the invention.

FIG. 6A is a plan view, FIG. 6B is a front view, FIG. 6C is a bottom view, FIG. 7A is a back view, FIG. 7B is a left lateral view, FIG. 7C is a right lateral view, and FIG. 7D is a perspective view. FIG. 8A is a perspective view of a state cut away along a line VIII-VIII in FIG. 7C viewed in a worm's eye manner. FIG. 8B is a cross-sectional view taken also along the line VIII-VIII. FIG. 9A is a perspective view of a state cut away along a line IX-IX in FIG. 6B. FIG. 9B is a cross-sectional view taken also along the line IX-IX.

In the exhaust gas cooling adapter 102 according to this embodiment of the invention, the blockage portion 124 at the center is located close to the exhaust manifold-side connection face 114 side, and is arranged at a position deviated from a cooling liquid flow channel 118 f at the center in the direction of the arrangement of exhaust gas flow channels 116.

Accordingly, in the direction of exhaust gas flow through the exhaust gas flow channels 116, a dent 124 c of a blockage portion 124 overlaps with a collision position of the flow of the cooling liquid flowing through the cooling liquid flow channel 118 f at the center as shown in FIG. 9B, but is actually deviated in the direction of the arrangement of the exhaust gas flow channels 116 (rightward in the drawing) as shown in FIG. 8B. Thus, the dent 124 c of the blockage portion 124 is arranged at a position other than the collision position of the cooling liquid flowing through the cooling liquid flow channel 118 f.

The exhaust gas cooling adapter 102 according to this embodiment of the invention is identical in basic construction to the exhaust gas cooling adapter according to the foregoing first embodiment of the invention except in that a bolt fastening portion 114 a of the exhaust manifold-side connection face 114 connected to the exhaust manifold 106 is changed in shape in accordance with this arrangement of the blockage portion 124.

That is, a bolt fastening portion 110 a of a cylinder head-side connection face 110 connected to a cylinder head 104, other two blockage portions 126 and 128, a cooling liquid introduction portion 120, a cooling liquid discharge portion 122, and the exhaust gas flow channels 116 are formed in the same manner as in the foregoing first embodiment of the invention.

According to the second embodiment of the invention described above, the following effects are obtained. (1) The dent 124 c of the blockage portion 124 according to this embodiment of the invention is also formed through an upper face of the cooling liquid flow channel 118 a located above in the vertical direction in the water jacket 118, but is deviated in the direction of the arrangement of the exhaust gas flow channels 116 to be located at a position with which the flow of the cooling liquid flowing through the cooling liquid flow channel 118 f does not collide. Thus, as described in the foregoing first embodiment of the invention, even when air enters the dent 124 c, the air in the dent 124 c is discharged without remaining bubbles due to the flow of the cooling liquid flowing away laterally as shown in FIG. 8B. Even when only the cooling liquid enters the dent 124 c, it is discharged and replaced in the same manner without dwelling therein.

In this manner, bubbles can be prevented from remaining in the water jacket 118 of the exhaust gas cooling adapter 102, and the cooling liquid can be prevented from dwelling therein. Therefore, even when the cooling liquid is heated due to the transmission of heat from the exhaust manifold 106 and the exhaust gas flowing through the exhaust flow channels 116, a decrease in cooling efficiency or boiling can be prevented from being caused.

Furthermore, before the through-hole 124 a is blocked with the plug body 124 b, the position of the through-hole 124 a is set such that the interior of the cooling liquid flow channel 118 f is visible via the through-hole 124 a. Thus, there is no hindrance to the removal of sand from the interior of the cooling liquid flow channel 118 f or the observation thereof.

Other Embodiments

In the foregoing first embodiment of the invention, each of the blockage portions is deviated from the position with which the flow of the cooling liquid through the cooling liquid flow channel collides, upstream in the direction of exhaust gas flow through a corresponding one of the exhaust gas flow channels. In the foregoing second embodiment of the invention, each of the blockage portions is deviated from the position with which the flow of the cooling liquid through a corresponding one of the cooling liquid flow channels collides, in the direction of the arrangement of the exhaust gas flow channels (downstream with respect to the flow of the cooling liquid).

Besides, if there is a position with which the flow of the cooling liquid does not collide downstream in the direction of exhaust gas flow through each of the exhaust flow channels, a corresponding one of the blockage portions may be deviated downstream in the direction of exhaust gas flow. Alternatively, each of the blockage portions may be deviated upstream with respect to the flow of the cooling liquid in the direction of the arrangement of the exhaust gas flow channels.

Alternatively, as is apparent from an exhaust gas cooling adapter 202 of FIG. 10, a blockage portion 224 may be deviated both in the direction of the arrangement of exhaust gas flow channels 216 and in the direction of exhaust gas flow through the exhaust gas flow channels 216 to be arranged at a position other than a collision position of the cooling liquid. FIG. 10A is a plan view of an exhaust gas cooling adapter 202, and FIG. 10B is a perspective view thereof.

This construction also produces the effects described in the foregoing first and second embodiments of the invention. In each of the foregoing embodiments of the invention, the regional coupling portion exists on the cylinder head side in each of the cooling liquid flow channels between the exhaust gas flow channels to enhance the rigidity of the exhaust gas cooling adapter. If no problem is caused in terms of rigidity when such a regional coupling portion is not provided, the entire spaces among the exhaust gas flow channels may be employed as the cooling liquid flow channels especially in the examples of the second embodiment of the invention and FIG. 10. This construction also produces the effects described above.

In each of the foregoing embodiments of the invention, the interval among the exhaust gas introduction ports through the cylinder head-side connection face is made larger than the interval among the exhaust gas discharge ports through the exhaust manifold-side connection face. This corresponds to the interval among the exhaust ports of the cylinder head to which the exhaust gas cooling adapter is applied and the interval among the opening portions of the exhaust manifold. Accordingly, when the cylinder head or the exhaust manifold assumes a certain shape, the interval among the exhaust gas introduction ports and the interval among the exhaust gas discharge ports may be equal to each other, or on the contrary, the interval among the exhaust gas discharge ports may be larger than the interval among the exhaust gas introduction ports.

While the invention has been described with reference to example embodiments thereof, it is to be understood that the invention is not limited to the described embodiments or constructions. The invention is intended to cover various modifications and equivalent arrangements. In addition, while the various elements of the disclosed invention are shown in various example combinations and configurations, other combinations and configurations, including more, less or only a single element, are also within the scope of the appended claims. 

1. An exhaust gas cooling adapter arranged between an exhaust port opening to a cylinder head of an internal combustion engine and an exhaust manifold, comprising: an exhaust gas flow channel which is provided inside the exhaust gas cooling adapter and through which an exhaust gas from the exhaust port flows to the exhaust manifold; and a cooling liquid flow channel formed in a wall portion of the exhaust gas cooling adapter that surrounds the exhaust gas flow channel, to cool the exhaust gas flowing through the exhaust gas flow channel, wherein the wall portion of the exhaust gas cooling adapter has a blockage portion formed by blocking a through-hole provided between an outside and the cooling liquid flow channel, and the blockage portion has a region located in the cooling liquid flow channel and arranged at a position other than a collision position of a cooling liquid flowing through the cooling liquid flow channel.
 2. The exhaust gas cooling adapter according to claim 1, wherein the wall portion where the blockage portion is formed is provided above the cooling liquid flow channel in a vertical direction in a state of being arranged between the exhaust port opening to the cylinder head of the internal combustion engine and the exhaust manifold.
 3. The exhaust gas cooling adapter according to claim 1, wherein the wall portion is cast, the through-hole is a sand removal hole for removing cast sand constituting a core forming the cooling liquid flow channel, and the blockage portion is blocked with a plug body.
 4. The exhaust gas cooling adapter according to claim 1, wherein a plurality of the exhaust gas flow channel are provided in arrangement, and the collision position of the cooling liquid is a position where a cooling liquid flow channel formed between the arranged exhaust gas flow channels is connected to another cooling liquid flow channel formed around the arranged exhaust gas flow channels.
 5. The exhaust gas cooling adapter according to claim 4, wherein the region of the blockage portion located in the cooling liquid flow channel is arranged at the position other than the collision position of the cooling liquid by being deviated in at least one of a direction of arrangement of the exhaust gas flow channels and a direction of exhaust gas flow in the exhaust gas flow channels from the collision position of the cooling liquid flowing through the cooling liquid flow channel.
 6. The exhaust gas cooling adapter according to claim 5, wherein the region of the blockage portion located in the cooling liquid flow channel is deviated in the direction of exhaust gas flow in the exhaust gas flow channels from the collision position of the cooling liquid flowing through the cooling liquid flow channel.
 7. The exhaust gas cooling adapter according to claim 5, wherein the region of the blockage portion located in the cooling liquid flow channel is deviated in the direction of arrangement of the exhaust gas flow channels from the collision position of the cooling liquid flowing through the cooling liquid flow channel.
 8. The exhaust gas cooling adapter according to claim 5, wherein the region of the blockage portion located in the cooling liquid flow channel is deviated both in the direction of exhaust gas flow in the exhaust gas flow channels and in the direction of arrangement of the exhaust gas flow channels from the collision position of the cooling liquid flowing through the cooling liquid flow channel.
 9. The exhaust gas cooling adapter according to claim 1, wherein the through-hole is positioned, before being blocked, such that an interior of the cooling liquid flow channel with which the cooling liquid collides is visible via the through-hole. 